Veteran RealSense developer Samontab advised, like you suggested, disabling the R200's IR emitter with scripting, since over-exposure of light could reduce the R200's capture quality. Here is the documentation page for that function.
Someone tried following this advice to disable the emitter and said that it improved their capture in strong sunlight.
There is also a laser configuration program for the Librealsense open-source SDK called cpp-config-ui.
Edit: I dug up a bit more info on the subject. "Turning on color stream auto exposure may lower the color stream frame rate in the low-light condition."
And, again from Samontab:
"When [the R200] is indoors, it acts as an active IR stereo camera, and when it is outside, it acts as a passive IR stereo camera."
Thank you Marty for your response. I shall look into trying your suggestions out and also the laser configuration UI.
I guess an alternative could be to use additional lighting to light up the low lit areas for good RGB data.
Yes, sometimes a simple low-tech solution (like additional lighting) is as good as a complex high-tech one.
There is another laser configuration tool available that was created by Samontab, though I didn't recommend it as a primary option because it has some caveats.
1. It was designed for the F200 camera and has not been proven to work with R200.
2. As it is an old application, it apparently needs to be run in the 'Windows 8.1 compatibility mode' of Windows 10. Or Windows 8.1 itself, if you have an old PC!